When to use js concat

concat() method is used to concatenate two or more arrays.

This method does not change the existing array, but only returns a copy of the connected array.

Syntax

arrayObject.concat(arrayX,arrayX,......,arrayX)

Parameters:

arrayX Required. This parameter can be a specific value or an array object. Can be any number.

Return value

Returns a new array. The array is generated by adding all arrayX parameters to arrayObject. If the argument to concat() is an array, then the elements in the array are added, not the array.

Example 1:

In this example, we will connect the parameters in concat() to array a:

<script type="text/javascript">

var a = [1,2,3];
document.write(a.concat(4,5));

</script>

Output:

1,2,3,4,5

Example 2

In this example, we create two arrays and then use concat() to concatenate them:

<script type="text/javascript">

var arr = new Array(3)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"

var arr2 = new Array(3)
arr2[0] = "James"
arr2[1] = "Adrew"
arr2[2] = "Martin"

document.write(arr.concat(arr2))

</script>

Output:

George,John,Thomas,James,Adrew,Martin

Related learning recommendations: js video tutorial

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